Back brace



FIG. 1 is a black and white photograph of a perspective view of a backbrace, showing my new design;

FIG. 2 is a black and white photograph of a front elevation viewthereof;

FIG. 3 is a black and white photograph of a rear elevation view thereof;

FIG. 4 is a black and white photograph of a left side elevation viewthereof;

FIG. 5 is a black and white photograph of a right side elevation viewthereof;

FIG. 6 is a black and white photograph of a top plan view thereof; and,

FIG. 7 is a black and white photograph of a bottom plan view thereof.

CLAIM The ornamental design for a back brace, as shown and described.